Many people shorten their URLs. But as per my understanding it creates overhead of extra redirection, other can not guess about the target article with their url, and it should be less friendly for "inurl:..." type search.

Should I shorten the URLs of my sites?

Is there any advantage with short URLs besides the fact that they take fewer characters in anchor tags on the page (good for site loading)?

describes the content (instead of just using a random article ID number)

shows the site structure (e.g. http://foo/artists/acid_bath/lyrics)

A short URL doesn't create any extra overhead—at least not in the conventional usage of the word—it just obfuscates the URL and, if it doesn't use a 301 redirect, interferes with proper PageRank flow.

The only reason to use URL shorteners is for services like Twitter, where you have a low character limit, or for mobile users for whom it's difficult to type long URLs.

In most cases, you should just generate a slug from the page title. Doing so gets rid of any special characters and unnecessary articles or conjunctions. This shortens the URL while keeping it descriptive and user-friendly.

Matt Cutts goes over keywords in URI's in a couple of videos. Showing site structure as in your example isn't really needed if the URL is generally short and to the point. (e.g. http://foo.com/artists/acid-bath-lyrics) is also ok. Matt also points out that you should use hyphens rather than underscores since an underscore is ignored and both words are combined. So acid_bath would be seen by Google as acidbath
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AnagioMay 23 '12 at 12:27

@Anagio: The example URL you give is semantically incorrect, as it's akin to saying there's an artist named "acid bath lyrics", or that there's a file called "acid-bath-lyrics" in the "artists" folder. The reason you use URLs that correspond with your site structure is for usability, not SEO. I.e. if a user sees /artists/acid_bath/lyrics, they know to go to /artists/acid_bath to find more on that artist or to /artists to browse other artists. But that's an interesting tip about underscores.
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Lèse majestéMay 23 '12 at 18:48

At MozCon last year there were a few presenters who indicated that the shorter the URL the better. You see a lot of retailers using http://example.com/product_id these days. Evidence has shown that keyword stuffing your URL ex. http://example.com/mens/shoes/opentoed/for/midgets/that/like/boxing/stupid_long_product_name offers no advantage.

Along the same lines, it seems that having a semantic URL is important but the article or product name might not be necessary. I need to find some references for this.

As an observation some retailers and magazine use a unique number in the URL and title to avoid duplicate title issues. Not sure if this actually works or not.

I'd be interested in seeing some empirical evidence for the irrelevance of descriptive URLs. Keyword stuffing is spammy and sure to get you penalized, but I'd be very surprised if search engines didn't use it for calculating search relevance at all, even if it's not as prominent a factor as before.
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Lèse majestéMay 23 '12 at 9:13

Those less characters won't speed up you page loading process for sure, but you can try and keep your links short in the first place. Also, a simple URL shortener is easy to build, so you can build one for every site you have.

That is the technical answer, meaning you can do shortening "longer" but "friendlier". SEO-wise, I suggest that as long as you have friendly (human-readable) URLs, keep them that way. Take the URL of this page as an example.